1. Field of the Invention
The present invention relates to an unwanted mail discriminating apparatus for discriminating whether e-mail is unwanted mail, and to an unwanted mail discriminating method in the apparatus.
2. Related Background of the Invention
The existing typical measures against unwanted mail (spam), such as phishing scams, include one using a blacklist. The details of this are described, for example, in JP-A 2003-150513 which is a Japanese Patent Application Laid-Open. The blacklist is, for example, a list of mail addresses, IP (Internet Protocol) addresses, or domains subject to rejection of reception. The measure against unwanted mail with the blacklist is to acquire the foregoing information from the header of e-mail and to compare the information with the information in the list, thereby discriminating whether the e-mail is unwanted mail. The measures against phishing mail further include a measure using a blacklist containing URLs (Uniform Resource Locators) of phishing sites.
Another typical measure is one using a whitelist. The whitelist is, for example, a list of mail addresses, IP addresses, or domains subject to permission of reception, and mail from senders other than those in the list is not delivered.
In addition to the above measures, there is the Sender ID framework as a method recently drawing attention. This framework involves managing a list of IP addresses of authorized servers that are permitted to transmit mail of a certain domain. If one attempts to send mail with a false origin by making use of a mail server unrelated to the domain, the receiver side will detect it and automatically reject reception thereof. This can prevent senders of unwanted mail from utilizing a mail address including a popular domain name, such as a major provider.